[Greasemonkey] Re: Greasemonkey or a filtering proxy?

Presto Wk prestowk at gmail.com
Sun Sep 11 00:09:09 EDT 2005

Jeff Barr <jeff at vertexdev.com> writes:

> If all that you want to do is simple text filtering, then a filtering
> proxy could do this just as well as Greasemonkey.
> However, Greasemonkey lets you do a lot more than simple text
> filtering. By providing full read-write access to the parsed object
> model of the page (the DOM), Greasemonkey is powerful enough to admit
> scripts that inspect, change, and capture events across the entire
> page. A filtering proxy would essentially have to be a full-fledged
> browser in order to do all of this, and I think that the programming
> model for such a beast would be a lot harder to learn. I don't even
> want to think about how hard it would be to deal with events across
> what would end up as two tiers of web servers.

It is possible that I do not fully understand Greasemonkey, and I am
certainly not experienced with JavaScript/DOM.  Therefore I need to
ask a question: wouldn't a JavaScript snippet provided in a HTML page
have full read-write access to the page DOM?  If so, I fail to see why
a filtering proxy could not achieve what Greasemonkey does: the
filtering proxy could simply modify the page textually to have the
desired JavaScript executed.

> Greasemonkey puts the power in the hands of the user. Getting
> corporate IT to install Greasemonkey-like scripts on a filtering proxy
> would end up as a bureaucratic nightmare in many organizations.

You are thinking of a site-wide proxy.  I'm thinking of a personal
proxy that you install on the same machine as your web browser.  As
far as I can tell a proxy can be a pretty light-weight process.

> Finally, having the work take place in the browser makes everything
> totally transparent. A knowledgable user can see exactly what scripts
> are applied and what they are doing. There are all sorts of dastardly
> things that could be done with access to a filtering proxy that wasn't
> totally accessible, configurable, and transparent.

With a personal proxy none of these points are valid: you are fully in
charge of your personal proxy, which allows you to inspect what
modifications would apply to any URL.


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